Updated

Top seeds John Isner and Kevin Anderson were challenged a bit more than expected, but both were second round winners at the BB&T Atlanta Open on Thursday.

Isner, a two-time finalist at this tournament, needed 2 hours and 28 minutes to dispose of fellow American Christian Harrison, a 19-year-old wild card. Isner rallied late to claim a 7-6 (11-9), 4-6, 7-5 victory.

Anderson, the No. 2 seed, dropped the first set against qualifier Matthew Ebden before running to a 6-7 (7-9), 6-2, 6-2 victory in just under two hours time.

James Blake will await Isner in quarterfinal play after knocking out eighth- seeded Russian Evgeny Donskoy in 6-3, 6-2 fashion. Russian Denis Istomin will take on Anderson after earning a 7-5, 6-2 victory against fifth-seed Yen-Hsun Lu.

American Ryan Harrison will also advance to the quarters after sending fourth- seeded Igor Sijsling packing in straight sets, 6-4, 6-3.

Lastly, Colombian Santiago Giraldo was ahead 5-7, 6-3, 3-0 when 35-year-old Michael Russell retired. Russell had won nine of his last 10 matches and was the oldest player left in the field. Harrison and Giraldo will square off against one another in the quarters.

The winner of this tournament will receive $98,700.